1. Field of Invention
The invention related to a method of prevention of particle pollution in a pre-clean chamber, in particular, to a method for preventing particle pollution in a pre-clean chamber of a physical vapor deposition (PVD) device.
2. Related Art
During a procedure of integrated circuit (IC) manufacture, PVD devices are employed to deposite thin metal film. PVD devices, as shown in FIG. 1, include mainly a buffer chamber 1, a pre-clean chamber 2, a transfer chamber 3, a process chamber 4 and a robot arm 5.
Wherein, the pre-clean chamber 2 addresses the cleaning procedure of a Wafer 6. As illustrated in FIG. 2, the pre-clean chamber 2 includes a radio frequency (RF) generator 21, a bell-jar 22, a shield 23 and a pre-clean chamber body 24. During cleaning a wafer 6, the wafer 6 is moved by the robot arm 5 into the pre-clean chamber 2, and then argon gas is injected into the pre-clean chamber 2 to be ionized into plasma using the RF wave from the RF generator 21. (as illustrated in FIG. 3). Thereafter, the plasma produced above is sputtered onto the wafer 6 to clean the surface of wafer 6.
As described above, due to plasma sputtering in the procedure of cleaning wafers 6 some parts of the wafer 6 would be split off onto the bell-jar 22 and the shield 23. Meanwhile, when the metal deposition in PVD is that of a gate procedure, the majority of the parts split off the wafer 6 are silicon, in other words, after some pre-clearings, a large amount of silicon-rich oxide will accumulate on the bell-jar 22 and the shield 23.
In general, the bell-jar 22 are made of quartz onto which silicon-rich oxide can not adhere well, and so peeling-off occurs to pollute the pre-clean chamber 2 and the wafer 6 therein when there is a big amount of silicon-rich oxide accumulating on bell-jar 22.
After all, the pollution will cut the efficiency of the following process. To solve this problem, manufacturers in this industry have to clean the bell-jar 22 from time to time to prevent the pollution of particles peeling off from the bell-jar 22.
However, cleaning the bell-jar 22 means stopping of manufacturing, and lower efficiency. And so, how to prolong the life of the bell-jar 22 of the pre-clean chamber 2 and to reduce time for cleaning the bell-jar 22 is the key for efficiency in this business.
With problem as above, the objective of this invention is to lessen the particle pollution of pre-clean chambers, to prolong the life of bell-jars, to cut short the frequency of clearing of bell-jars 22 and to upgrade the efficiency of the production line.
The method for preventing particle pollution in a pre-clean chamber according to the invention is featured by injecting oxygen gas into the pre-clean chamber, and ionizing the oxygen gas therein by RF wave into plasma, which would interacts with silicon-rich oxide split off a wafer to form a silicon oxide layer to cover the bell-jar. And so, peeling-off of silicon-rich oxide is prevented by a layer of silicon oxide and the life of the bell-jars is prolonged.
To achieve the object mentioned above, a method for rapid preventing particles in a pre-clean chamber according to the invention includes following steps:
An oxygen gas supplying step for injecting oxygen gas into a pre-clean chamber, and
A plasma generating step for electrify the oxygen gas therein into plasma by RF wave, and then the plasma produced above interacts with silicon-rich oxide to form a silicon oxide layer in the pre-clean chamber.
Wherein, due to better adherence of the silica and the bell-jar, the interaction of the oxygen gas and the silicon-rich oxide formed on the bell-jar of the pre-clean chamber produces the silicon oxide layer so as to avoid the peeling of silicon-rich oxide off the bell-jar, and to prolong the life of the bell-jar.